Sagi received a 9-month prison sentence in 1996 for "grave deceit, bribery and insider trading", after being found guilty of manipulating bond prices in Israel in 1994. This followed a plea bargain with the district court in Tel Aviv.
Sagi owns 6.3% of the company, which he founded in 1999. It was floated in 2006 on the London Stock Exchange at a price that valued the Business at approximately £550 million.
Since 2010, Sagi has been living with Yael Nizri, the 2006 Miss Israel, and they have two daughters together. Sagi owns the most expensive home in Israel, located in Herzliya. The home, which he bought in 2010, lies in the wealthy neighborhood of Herzliya Pituah on Galei Techelet Street, Israel's most expensive street. It is a 2,000 square meter house on a half-acre lot on the shore, and has a fitness room, wine cellar, sealed room, and an elevator to the beach. Sagi also owns two penthouses in Herzliya, and other homes in Tel Aviv (including an apartment in the Tzameret Towers purchased from former Israeli Prime Minister Ehud Barak), London's Knightsbridge, Cyprus, and Berlin.
In late 2012 Sagi acquired the start-up company Crossrider for $US 37M. The company went public on AIM at a value of $US 250M. It is an application distribution and digital products platform.
In 2013, The Guardian reported that Sagi had "been based in Cyprus for some years".
Camden Market Holdings, the owner of Camden Market, Stables Market and Camden Lock Developments was bought by Sagi in March 2014 for £400 million (US$664 million) from Bebo Kobo (50% owner), and Richard Caring and Elliott Bernerd for 2.3-2.6Bn ILS, which later turned out to be the biggest LSE IPO of 2015. Sagi has continued to buy property in the Camden Market area and as of March 2015, owns the four most important of the six sections of the market, London's second most popular tourist attraction after Buckingham Palace.
In June 2017 Sagi acquired 44% of Brack Capital Properties N.V, which is a listed real estate company, owning and developing residential and commercial properties in Germany.
Sagi intends to invest £300 million in developing the market area by 2018.